Code
P1282
GM
P — Powertrain
Accelerator Pedal Position Sensor 2 Circuit Low Voltage
Views:
UK: 36
EN: 57
RU: 38
AI status
Completed
Completed
100%
Causes
- Damaged or shorted signal wire to ground
- Open circuit or high-resistance connection in sensor wiring
- Corroded or loose pedal sensor connector
- Failed accelerator pedal position sensor (sensor 2)
- Poor or missing sensor ground or reference voltage
- Water intrusion or contamination of pedal connector
Symptoms
- Malfunction Indicator Lamp (MIL) / Check Engine Light illuminated
- Reduced engine power / limp mode or limited throttle response
- Unresponsive or inconsistent accelerator pedal feel
- Throttle may hang at idle or vehicle refuses to accelerate
- Stored freeze frame and DTC data showing low sensor 2 voltage
What to check
- Read and record freeze frame and live data with a scan tool (monitor APP Sensor 1 and Sensor 2, PCM reference voltage, and DTCs)
- Visually inspect pedal connector and wiring for corrosion, damage, or pinched sections
- Verify 5V reference and sensor ground at the pedal connector with key ON (use backprobe)
- Measure APP Sensor 2 signal voltage at connector with key ON and while moving pedal
- Perform wiggle test of harness and connector while monitoring live data for intermittent changes
- Check continuity between pedal signal pin and PCM input, and continuity for ground and 5V reference
Signal parameters
- Sensor type: typically three-wire potentiometer/hall-effect (5V reference, signal, ground)
- Reference voltage: approximately 5.0 V (tested at sensor reference pin with key ON)
- Expected sensor 2 output: ~0.5 V (pedal at rest) to ~4.5 V (pedal depressed) depending on design
- Low-voltage fault threshold: sensor 2 signal below approximately 0.2–0.5 V may set P1282 (manufacturer threshold varies)
- Compare sensor 1 and sensor 2 ramping behavior — both should change smoothly and correlate (often different slope or offset)
Diagnostic algorithm
- Retrieve and record freeze frame, pending codes and live data (monitor APP Sensor 1 & 2 and PCM 5V ref)
- Inspect pedal assembly and harness for physical damage, corrosion, or water entry. Repair any obvious issues.
- With key ON (engine OFF) backprobe the pedal connector: verify ~5V at reference terminal, solid ground at ground terminal, and measure sensor 2 signal voltage at rest.
- Operate pedal slowly while observing sensor 2 voltage: it should move smoothly from rest toward full-range. If the signal stays low or does not change, continue.
- If reference or ground missing, trace wiring back to fuse/ECM and repair open or corroded connections. Check for blown fuse or poor chassis battery ground.
- If 5V and ground present but signal is low, check continuity between the sensor 2 signal pin and the PCM input. Repair any short to ground or open circuit.
- Swap/compare to sensor 1 behavior on the scan tool — if sensor 1 behaves normally while sensor 2 stays low, the pedal sensor 2 is suspect.
- If wiring and connectors test good and problem persists, replace the accelerator pedal assembly (contains the sensors).
- After repair, clear codes and perform a test drive to confirm no return of P1282 and that APP sensor voltages track as expected.
- If new sensor still reports low voltage and wiring checks to PCM are good, suspect PCM input fault — refer to manufacturer procedures before replacement.
Likely causes
- Shorted signal wire to chassis ground between pedal and ECM
- Corroded/loose connector at pedal harness
- Failed pedal assembly/sensor 2 element
- Broken or pinched harness in driver footwell area
- Poor sensor ground or 5V reference feed
Fault status
Status
P1282 — Accelerator Pedal Position Sensor 2 Circuit Low Voltage. PCM detected APP sensor 2 signal below expected threshold. Check pedal sensor, wiring, reference 5V and ground.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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